Thermal expansion studies of stishovite at 10.5 GPa using synchrotron radiation

The thermal expansion of stishovite has been studied in situ under pressure at 10.5(8) GPa and in the temperature range from 20 degrees C to 1000 degrees C using a cubic type apparatus combined with synchrotron radiation. The linear thermal expansivities along the crystallographic a- and c-axes at 10.5(8) GPa and 20 degrees C are alpha(a) = 0.4978(1) x 10(-6) K-1 and alpha(c) = 3.155(2) x 10(-6) K-1, respectively. The volume thermal expansivity for the same pressure-temperature conditions is alpha(v) = 4.080(4) x 10(-6) K-1. The Anderson-Gruneisen parameter, delta(T), at 10.5(8) GPa decreases with increasing temperature from 55 at 20 degrees C to 15 at 1000 degrees C, and approaches five when extrapolated to 1500 degrees C.